Preparation and Evaluation of a New Lipopolysaccharide-based Conjugate as a Vaccine Candidate for Brucellosis.

OBJECTIVES: Development of an efficacious vaccine against brucellosis has been a challenge for scientists for many years. At present, there is no licensed vaccine against human brucellosis. To overcome this problem, currently, antigenic determinants of Brucella cell wall such as Lipopolysaccharide (LPS) are considered as potential candidates to develop subunit vaccines. METHODS: In this study, Brucella abortus LPS was used for conjugation to Neisseria meningitidis serogroup B outer membrane vesicle (OMV) as carrier protein using carbodiimide and adipic acid-mediated coupling and linking, respectively. Groups of eight BALB/c mice were injected subcutaneously with 10 µg LPS alone, combined LPS + OMV and conjugated LPS-OMV on 0 days, 14 days, 28 days and 42 days. Anti-LPS IgG was measured in serum. RESULTS: The yield of LPS to OMV in LPS-OMV conjugate was 46.55%, on the basis of carbohydrate content. The ratio for LPS to OMV was 4.07. The LPS-OMV conjugate was the most immunogenic compound that stimulated following the first injection with increased IgG titer of ∼5-fold and ∼1.3-fold higher than that produced against LPS and LPS in noncovalent complex to OMV (LPS + OMV), respectively. The highest anti-LPS IgG titer was detected 2 weeks after the third injection (Day 42) of LPS-OMV conjugate. The conjugated compound elicited higher titers of IgG than LPS + OMV, that showed a 100-120-fold rise of anti-LPS IgG in mice. CONCLUSION: These results indicate that our conjugated LPS-OMV can be used as a brucellosis vaccine, but further investigation is required.

Lamivudine-PEGylated chitosan: a novel effective nanosized antiretroviral agent.

Due to the fact that a definite treatment for AIDS disease has not been discovered so far, antiretroviral drugs are relatively significant in controlling the disease. In this study, Lamivudine- which is an old and effective anti-AIDS drug- was connected to PEGylated chitosan nanoparticle in order to produce a new and greater version of Lamivudine. First, physicochemical studies such as HNMR, FTIR spectroscopy and CHN analysis were performed to ensure the proper synthesis. Following that, Lamivudine-PEGylated Chitosan (LPC) drug was evaluated in terms of its inhibitory capability in producing HIV virions and its cytotoxicity in different doses. HIV virions were created by transfection of psPAX2, PmzNL4-3 and pMD2.G plasmids into HEK293T cell line. Also, assessment of the P24 amounts of cell supernatant was performed using ELISA method. Among the different doses of LPC drug (0.1, 1, 10 and 100µM), it was found that 0.1µM was the most effective and least toxic dose compared to Lamivudine in the same dose. Results of this study indicate that LPC drug has the ability to inhibit HIV virus replication in a more significant way in comparison to the old drug. Besides, the drug has a low cytotoxicity and is effective with a lower dose.